Electron energy loss spectroscopy and X-ray emission spectroscopy have been used to analyze foreign particles in electron microscopy samples taken from lung biopsies and lavages of Clinical Center cases with known exposure to various reagents. In several cases chronic granulomatous lung disease was present. Thin sections of tissue in the granuloma regions showed the presence of particles in macrophages. In one case of exposure to volcanic ash, alumnosilicates were found; titanium was found in another case where exposure had been suspected. The particles which ranged in size from 20 to 200 nm were also imaged with X-rays so that an elemental map could be superimposed on a scanning transmission micrograph. This type of microanalysis is the only method available for identifying such small particles embedded in tissue, and demonstrates a useful clinical application of the analytical electron microscope.